Salinity dropping and rising by 6ppt during the day & night.

[Sacohen]

My Salinity meter is reporting strange levels.

As you can see in the attached shot from the portal it is rising and dropping through the day and night by around 6ppt.



My water level is stable around 32% and is being maintained by RO/DI water with Kalkwasser mixed in it.
Right now the ATO code in my RA is being by passed because it seemed to be going on at time when it was not directed to (different issue) so I have been manually turning it on and off from work or where ever thru my phone of internet.

I thought there was an issue with the probe because if I re-calibrated it the levels would got back to where they should be (around 35-36ppt) and a hydrometer seems to reflect the equivalent SG levels, but I did not re-calibrate the probe yesterday and as you can see the Salinity jumped from 32ppt to 38ppt at around 1am and then back down from 35ppt to 30ppt at 1pm this afternoon.

1am and 1pm is the time that my de-nitrification chamber dumps water back into the sump from the chamber, but it also does it at 7am and 7pm and there are no drastic changes in Salinity at those times.

Any suggestions or help appreciated.

[rimai]

Did you try moving the probe around?

[Sacohen]

I don't have a lot of room in my sump.
I can try that over the weekend, but it has been pretty stable since I put it in about a month ago.

This just started happening about a 1 1/2 ago.

At first I thought it was the ATO pump going on when it was not needed, and it may have been back a week ago, but I've since disabled the ATO code and it is still happening.

[farkwar]

What I see is that your pH is dropping at the same time. Which is when you're having the spike in conductivity (salinity). The salinity probe doesnt really measure salinity but the conductivity of the water. If one were a chemist I would assume that some liquid with electrolytes could be fashioned to read 35ppt and have no Na or Cl in the liquid.



edit, what I wrote initially doesn't make sense, so I deleted it(if it were the kalk the pH would go high). Why is your pH dropping at that time, getting more acidic at those times?

Something is dropping your pH quickly then rebounding quickly. Do you have a fan that turns on/off at that time, CO2 reactor?

[Sacohen]

No the Fan runs all the time from 1 pm to 9 pm when the daylights are on.

The pH drop could be that I pulled the probe holder out )My Sump Temp probe, Grounding probe Salinity probe and pH probe so I could re-calibrate the Salinity probe so at that point the [H [rpbe was out of the water and not measuring anything so that would explain the drop.